Characterization of sol-gel synthesised lead-free (1-x)Na0.5Bi0.5TiO3-xBaTiO3-based ceramics

The crystal structure, microstructure, dielectric and ferroelectric properties of (1 - x)Na0.5Bi0.5TiO3-xBaTiO(3) ceramics with x = 0, 0.03, 0.05, 0.07 and 0.1 are investigated. A structural variation according to the system composition was investigated by X-ray diffraction (XRD) analyses. The results revealed that the synthesis temperature for pure perovskite phase powder prepared by the present sol-gel process is much lower (800 degrees C), and a rhombohedral-tetragonal morphotropic phase boundary (MPB) is found for x = 0.07 composition which showing the highest remanent polarization value and the smallest coercive field. The optimum dielectric and piezoelectric properties were found with the 0.93Na(0.5)Bi(0.5)TiO(3)-0.07BaTiO(3) composition. The piezoelectric constant d(33) is 120 pC/N and good polarization behaviour was observed with remanent polarization (P-r) of 12.18 pC/cm(2), coercive field (E-c) of 2.11 kV/mm, and enhanced dielectric properties epsilon(r) > 1500 at room temperature. The 0.93Na(0.5)Bi(0.5)TiO(3)-0.07BaTiO(3)-based ceramic is a promising lead-free piezoelectric candidate for applications in different devices. (C) 2011 Elsevier B. V. All rights reserved.